Ashutosh Pandey
Technical Head,
ETv News Network

Terrestrial Broadcasting Or VoD Over Cellular Networks Is The Question Before Us

One of the factors limiting the future of communications is bandwidth. In particular, mobile providers are greedily eyeing the 470-790 MHz frequencies currently used for conventional TV broadcasts. The current

model is to send the same data to all destinations, a process called broadcasting. So everybody watches the same content at the same time. The advantages of this system are that it guarantees everybody the same high level of service since they all have access to the same signal. It is also relatively cheap to continue with because most people already have the necessary receiving equipment.

By contrast, there is a growing interest in sending different data streams to each user over a cellular network, a process known as unicasting. The big advantage here is that users get video-on-demand allowing them to watch whatever they want, whenever they like. But there are challenges as well. It is much harder to guarantee all users the same high level of performance, particularly those in rural areas at the edge of the network. What is more, the infrastructure necessary to provide this cellular service is expensive both for providers to build and for users who need to upgrade their own kits.

The question is how these various factors balance out given reasonable assumptions on future demand.

The answer lies in the unicast-dominated option over a cellular network– CellTV. The sobering conclusion is that while CellTV has benefits, it is by no means clear that it makes sense to switch in the near future. These approach the problem by modeling the future evolution of cellular networks and terrestrial TV broadcasting. The argument is that we need to figure out an area which has a good combination of isolated rural districts and densely populated towns. It should have a highly developed cellular network as well as terrestrial TV coverage that rivals the best in many countries. Statistics show how these two systems are used. The reasonable assumptions about the advances that will be possible with cellular networks by 2020 can be made and then a decision taken whether it makes sense to switch to a cellular-based TV system by then.

The key factor in all this is the way television is viewed. Currently, a large number of viewers watch a limited number of channels. This is ideal for a conventional terrestrial broadcasting system. However, video-on-demand allows a large number of channels to be watched by a small number of viewers, a system that is ideal for cellular-based unicasting. So the crucial question is how viewing habits are likely to change by 2020. Unfortunately, we do not have an answer to this. An analysis shows that CellTV can be beneficial if the current trend toward more specialized programming, more local content, and more on-demand requests, continues.

We can also say: Our work also shows that CellTV is not effective in replacing terrestrial TV broadcasting for the current TV viewing patterns. If the change in the TV service is more modest and linear content is still the major part of the offering, then the gain would be limited. In that case, the deciding factor will be the cost of changing the system. When all the costs are added up, the prediction is decidedly conservative. It is doubtful that the expected spectrum saving can motivate the investments in both cellular sites and TV receivers.

By this analysis, we are going to have conventional terrestrial TV broadcasts for the foreseeable future.The problem, of course, is that this is a chicken and egg situation. It is hard to generate demand when the CellTV system does not exist and without demand, it is hard to justify the investment. There are other possibilities though. One is that the evolution of short-range services, such as the next generation of wi-fi, will drive demand for unicast services and thereby shape the future of television. Another is that TV over fixed-line broadband will come to dominate making terrestrial broadcasting obsolete. Only time will tell.

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